Valve assembly



Dec. 6, 1966 HlRoTo KoBAYAsr-ll ETAL 3,289,689

VALVE ASSEMBLY Filed Dec. 28, 1965 2 Sheets-Sheet 1 FIG! HIROTOKOBAYASHI 8x EY KOSAKU A1B/ARA Dec. 6, 1966 HlRoTo KOBAYASHI ETAL3,289,589

VALVE ASSEMBLY Filed Dec. 28, 1965 2 Sheets-Sheet 2 Q FULLY CLOSQC G E'l 3,289,689 VALVE ASSEMBLY Hiroto Kobayashi and Kosaku Aibara,Kawasaki, Japan, assignors to Kabushiki Kaisha Keihin Seiki Seisakusho,Kawasaki, Japan, a corporation of Japan Filed Dec. 28, 1965, Ser. No.517,023 3 Claims. (Cl. 137-221) This application is acontinuation-impart application of U.S. Serial No. 249,417 filed January4, 1963.

This invention relates broadly to valve assemblies and more specificallyto pilot-operated fluid shut-off, flow control valves, wherein a valvepiston is subjected to a pressure difference between the main upstreamand a pilot stream branched off therefrom and the latter stream iscontrolled by a pilot wave. Such a conventional valve assembly isgenerally so constructed that the main flow is completely shut-off whenthe pilot valve is closed to cease the pilot stream. Flow controlfeature can be also obtained when the pilot valve is made in the form ofa flow control valve. The back pressure acting upon the `main valvepiston exerted lby the pilot fluid pressure is generally assisted byspring means generally in the form of a coil.

According to the conventional technique, the piston is kept generally influid tight relation with the cooperating cylinder by means of aplurality of sealing rings or by fabricating the piston precisely, suchas by polishing the latter to the desired dimensions for preventingpossible leakage between the piston and the cylinder. Such a fluid tightcooperation requires naturally a large amount of effort to be exertedupon the piston for closing the latter, and the pilot valve must bedesigned correspondingly larger. When the pilot valve issolenoid-controlled, the required electrical power will become large,which means that a correspondingly large size solenoid coil is requiredand larger overall sizes of the valve assembly will result. lf the pilotvalve is operated by a oat, in the case of the fluid level controlvalve, the size of the float must also be designed correspondinglylarge.

A considera-ble and grave drawback inherent in the conventionalpilot-operated valve is that caused by the fluid hammer which takesplace upon closure of the main valve.

It is therefore an object of the present invention to provide apilot-operated valve of which the valve piston is movable in its closingdirection with a considerably reduced effort in comparison withconventional valves.

Another object of the invention is to provide an improved pilot-operatedvalve, capable of minimizing fluid hammer shocks which are commonly metupon sudden closure of the valve.

Another object is to provide an improved pilot-operated valve of whichthe valve pistonand the cooperating cylinder may be fabricated in theirpreciseness more roughly than conventional.

In addition to the provision of a considerable play between the valvepiston and the cooperating cylinder according to the invention, there isprovided efficient and resilient sealing means for the main valve aswell as the aforementioned leaking gap between the valve piston and thecylinder.

Another object of the present invention is therefore to provide animproved pilot-operated valve which assures smooth, bubble-tight anddrip-proof closing thereof.

A further object is to provide an improved pilotoperated valve of thekind above .referred to, which is rugged, and of simple construction,having few moving parts to insure long life and maintenance-freeope-ration.

These and other objects of t'he invention will be more apparent to thoseskilled in the art from a consideration United States Patent O 3,289,689Patented Dec. 6, 1966 lCC of the following detailed description whentaken together with the accompanying drawings in which:

FIG. 1 `represent a general longitudinal section of a a pilot-operated,solenoid-controlled shut-off valve ernbodying the principles of theinvention;

FIG. 2 represents a horizontal section taken on a plane 2-2 in FIG. l;

FIGS. 3A and 3B are a sectional view and a top plan view of a sealingring employable in the above-illustrated valve, respectively;

FIG. 4 is a longitudinal section through part of the improved valveassembly, wherein buffering means provided in front of the head of themain valve piston so as to suppress possible fluid hammer when closingthe valve are specifically illustrated;

FIG. 5 is a similar view to FIG. 4 showing especially a pin type.buffering means cooperating with the nozzle opening in the main valvepiston so as to buffer possible fluid hammer from taking place; and

FIG. 6 is a diagram showing buffering effects obtainable with use of theaforementioned buffering means shown in FIGS. 4 and 5 respectively.

Now referring to FIGS. l-2, an embodiment of the invention will bedescribed in detail hereinbelow:

10 denotes generally a two-piece valve body or casing comprising twoseparate casing elements 10a and 10b, which are detachably unitedtogether by means of a plurality of fixing bolts 11, of which only oneis illustrate-d in FIG. l. Centrally within the interior of the valvebody assembly 10, there is provided a core piece 12 rigidly fixed withthe casing wall by means of a plurality of radial ribs 13 cast integraltherewith. The core piece 12 is in practice divided into two elements asat 12a and 12b. For insuring a fluid tight connection between theconfronting surfaces of these elements, an O-ring 14 is provided "asconventionally.

In the similar way, a further O-ring 15 is provided for establishing asufficient seal between the confronting surfaces of the casing elements10a and 10b, The casing elements 10a and 10b are formed with inlet andoutlet passages 10c and 10d, respectively, said passages being connectedwith each other by means of a ring passage 10e as indicated by dottedlines in FIG. l. The core 12a is formed centrally with a stepped borecomprising a reduced portion 16a and an enlarged portion 16h, which boreis closed by the front wall surface of the other core element 12b Avalve member generally denoted by 17 passes loosely through the said.reduced portion or opening 16a with a considerable diametrical play suchas, for instance, about 0.2 mm. or larger for 50 mm (2) valve, extendinginto the enlarged core chamber 16b. The diametrioal gap will be reducedto about 0.06 mm. for 15.77 mmp (1/z") valve. As shown, the valve memberis divided into three elements, that is, a hollow cylindrical element 18having a radial flange 18a at its downstream end; a cone piece 19detachably fixed with the last mentioned element 18 by means of nutsZtl-21; and a nozzle piece 22 screwed in the cone at its apex. Aresilient sealing ring 23 is provided between the mating surfaces ofsaid members 18 and 19, and a narrow fluid passage 24 extends throughnozzleand cone pieces 22 and 19 and opens in the cylindrical innermostchamber 30. A coil spring 25 is contained within the chamber 3ft so asto urge resiliently the thus formed valve member assembly towards avalve seat 26 formed on the downstream end of the inlet passage 10c.Valve `seat 26 is adapted to cooperate with part of sealing ring 23, aswill be more fully described hereinafter. An angular fluid outletpassage 27a-27h is drilled through the downstream core element 12b, andterminates into an enlarged vertical bore 28, in which a plunger 29extends.

This plunger is slidably guided in a mounting member or bonnet 31, whichis detachably bolted to the uppermost at surface of the downstream valvecasing element b by means of a plurality of fixing bolts 32, only one ofthe latter is seen in FIG. l. For sealing connection between lthe matingsurfaces of casing element 10b and mounting member 31, O-ring 33 isprovided, `and in addition, for sealingly guiding the plunger, a glandassembly generally denoted by 34 is provided in the mounting member. Thelower end of the enlarged bore 28 is open to the main tiuid passage ofthe valve as at 35. A control lever 36 is pivotally mounted on themember 31 about a pivot 37, which is screwed therein, while the plungeris formed at its top end with an enlarged head and the free end ofcontrol lever is normally kept in engagement with thelovver surface ofthe plunger head. In this position, the lower end of the plunger is keptin separation a predetermined distance from the bottom of bore 2 8, sothat outlet passage 27 is in communication `with themain valve passageltlc-e-d. In the bottom end f plunger 29, resilient disc 38, preferablytriade from synthetic substance, such as, for instance, nylon, Teflon,Buns or the like, is embedded and adapted to cooperate 'with a valveseat 237e formed around the uppermost end of unici passage 27.1).Sealing means 23 may be magie from a substance s above listed.

, The plunger 29 has i'iiitegal extnsiri 35"', which is slidably munted.iii boss 40 fori-tied intgral Jit/'ith the bottom wall sie of a coilover easing 421, emerged by a coil spring 42 tensioned betweeii a collar49; on the one hand, which is formed on `an intermediate prtion of theplunger, and the bottom surface of the cover casing, on the other hand.The cover is provided with a plurality of depending legs 43, which arerigidly, yet detachably fixed on the upper surface of mounting member 31by means of bolts 44. The cover casing contains therein solenoid coil 45shown only schematically. Although not shown, the solenoid iselectrically connectedto a current source by means of suitable leads(not shown) which are inserted from outside through e socket 4o, formedin the clover wall as conventionally.

For the purpose which will becrre clear as the description proceeds, asealing ring 47 is mounted around the periphery of the cylindricalelement 18 and abuts upon the flange 18a.

This sealing ring', illustrated more fully in FIGS. 3A. and 3B, ispreferably made of suitable synthetic substance, such as, for' instance,nylon, Teflon, Buna or the like. This ring has a V peripheral groove asshown and is provided with a pressure member in the form of Colld spring48, which may be dispensed with, if necessary.

The valve assembly is further' provided with a shockbuiering meansgenerally shown in FIG. 1 by refer- 'ence symbol B and with an imaginaryline illustrating only the outline of the means for avoiding possibleco= fusion with other parts of the valve assembly.

In FIG. 4, the buffering means B effectively at the closing operation ofthe valve is shown more specifically. In this ligure, however, the valvebody 10 and the valve member 17 are illustrated only schematically andthus in a somewhat different manner, for the purpose of showing thebasic construction of the valve. Further, in this ligure, the part ofthe valve body 10 which denes the reduced yopening 16a shown in FIG. 1is illustrated for simplification as if it be aln independent sleeve10g. Still further, in FIG. 4 sealing ring 23 shown in FIG. 1 as fixedlymounted on valve member 17 has been omitted and instead a resilient ring23a is fixedly mounted on the part of valve body 10 which corresponds tovalve sea-t 26 shown in FIG. 1. In the wall of the cone part of thevalve member, a communicating passage 10h may preferably be provided.

As shown in FIG. 4, a stationary sleeve 101 is iixedly mounted by a rib102 extending from the inlet opening 10c of the valve body 10 in frontof resi-lient valve, seat Cil 23a. A double headed buffer member 104 isresiliently supported through the intermediary of a coil spring by thesleeve 101.

In a modication shown in FIG. 5, .the double headed member 104 describedin connection with FIG. 4 has been replaced by an elongated flow controlpin 108 lxedly mounted in sleeve 10161.

The valve assembly described so far is constructed as an on-off valve,and operates as follows:

A fluid, such as pressurized air, steam, vapor, water, oil or the like,is conveyed from an inlet piping (not shown) rigidly bolted to thelefthand side ange (FIG. 1), to inlet passage 10c, as indicated by anarrow X. When lthe valve assembly is maintained Iin its open position asshown in FIG. 1, substantial part of the inlet lluid Will flow throughring passage 10e to outlet passage 10d, while at the same time a smallquantity of the uid will ow as a pilot flow `into the narrow passage 24,thence through chamber 30, passages 27a27b, bore 28 and passage 35 intoa space in front of outlet opening 10d, whereby the pilot flow combineswith the main ow.

A leakage iiow will occur naturally `through a considerable large playor clearance between the cylinder member 18 and the reduced portion 16aof the core chamber. This iiow will finally reach the passage 27, butthis effect Will act only to increase the quantity of the pilot ilowabove described, so that no cause to adverse elcct upon the properfunctioning of the valve assembly results. On the contrary, theprovision of the aforementioned relatively lrge play will contributeconsiderably to obtain the' desirable smooth closing of the valve, aswill be more ful-ly described hereinafter.

When it is desired to close the valve, the control lever 36 is turnedclockwise in FIG. 2 so as to separate the the free end thereof from theplunger 29, thereby releasing the latter. whereupon, the plunger movesdown under the inuence of coil spring 42, until disc 38 restlientlyseats lupon seat y27C so as to close the related pilot passage 27b. Inthis way, the pilot llow is completely shut-off, so that the uid backpressure acting upon the main valve member assembly from inside thereofwill become predominant to overcome the main positive fluid pressureacting upon the outer surface of the piston. In this case, spring 25acts as an auxiliary means for closing the main valve. In general, thisauxiliary means may be dispensed with, thus relying solely upon thefluid pressure as above described.

In this way, the main valve will advance and finally occupy its closingposition, wherein the resilient ring 23 cooperates with the seat 26. Inthis position, the main flow is completely shut-down. The valveconstituents are so arranged and dimensioned that in the closingposition of the valve, the resilient ring 47 will effectively seal theaforementioned considerable gap along the valve casing Wall at 16a. Theabove-mentioned double sealing means comprising resilient rings 23 and47 operates effectively to keep the main and leakage huid streamscompletely shut-off.

The above-mentioned embodiment is of the manual reset type. When manualpressure is released from control handle 36 occupying its MF-position, areturning spring (FIG. 2.) acts yto rotate the handle clockwise in thesame figure so as to bring the free end thereof into abutting engagementwith the collar on plunger 29.

When the valve is to be re-opened, `a manual switch (not shown) isclosed so as to energize the solenoid coil 45 for attracting theplunger, and ythus the latter is elevated thereby until it occupies theoriginal position shown in FIG. 1. The out-let passage 27a-27b is thusopened to the main ow passage as before. In this Way, the pilot flow isinitiated and thus `the uid pressure prevailing in the valve chamber 30is caused to reduce, whereby the fluid valve opening pressure actingupon the valve cone 1.9 Will become .predominant so that the counter uidt3' pressure plus spring pressure :are overcome, whereby the main valvepiston is displaced in the opening direction, that is, righthandwards inFiG. 1. The main fluid flow is then established as before and dischargedfrom the discharge opening 10d as indicated by an arrow Y. The operatorturns the control lever 36 clockwise in FIG. 2 to the position shown int-he figure so as to engage with the plunger' 29 underneath its collar.The pilot flow from inlet opening 10c through passage 24, chamber- 3),passage 37, bore 28 and passage 35' to discharge opening 10d is thuscontinued. lf necessary, spring 42 and solenoid 45 may be reversed intheir action. More specifically, the solenoid may be designed andarranged for serving to close the pilot passage 35 with the coil spring42 serving to return the plunger to its opening position.

If necessary, the aforementioned switch may lbe so arranged that it iscontrolled by the control lever 36. With such arrangement, one touchmanipulation of lever 36 will produce the aforementioned valve openingor closing operation, as the case may be. It will be clear that with theembodiment described so far, wherein a considera-ble piston leakageclearance and an efficient double sealing mechanism are employed, thepiston movement is carried out in a `highly smooth manner so that thenecessary pilot flow is amazingly small in its rate. With such animproved construction, the whole valve assembly can be made highlycompact and the electrical energy for the control thereof will be small.

If necessary, the manual handle can be dispensed with and the valvingoperation may be controlled only by the solenoid coil, just as inconventional solenoid-operated valves.

It will be understood that as the piston advances, the pilot flowthrough the nozzle opening of the piston will tbe gradually reduced so.as to provide an effective action thereupon. In this way, adisadvantageous fluid hammer effect may be practically overcome.

Effective buffering effect provided by the above explained arrangements,specically shown FIGS. 4 and 5 can be clearly seen from -a diagram shownin FIG. 6. Dotted line A-BC represents a closing characteristic of thevalve shown in FIG. l. By the provision of the buffering means Bdescribed above in connection with FIG. 4, the closing characteristiccan lbe modied and improved as shown by a curve A-B-C, which means thata sudden closing effect has been amazingly buffered. A similar valve tothat shown in FIG. l, having a large fluid capacity similar to aconventional 5" valve, showed a closing characteristic curve A-D-E. Bythe provision of the needle type buffer described above in connectionwith FIG. 5, the curve was modified to line A-F-E, which representsagain a remarkable improvement for avoiding a possible fluid hammer.

Although the above embodiments are adapted to be used for relatively lowfluid pressure, for instance 5-200 p.s.i., the invention is not limitedthereto. With a slight modification to the aforementioned embodiment,any fluid lhaving a higher pressure such as for instance 2,000

p.s.i. can be equally treated. Although not shown, the lowermost end ofplunger 29 may be fabricated to form a pointed end so as to cooperatewith the uppermost end of passage 27b as a valve seat.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily -adapt it for various applications without omitting featuresthat, from the stand of prior art, fairly constitute essentialcharacteristics of the generic of specific aspects of this invention,and therefore, such adaptations should and are intended to becomprehended within the meaning and range of equiv* alence of thefollowing claims.

What is claimed as new and desired to be secured Letters Patent is:

l. In a pilot-operated valve assembly, t-he improvement comprising avalve body having a fluid inlet passage and a fluid discharge passage, ahollow piston slidably mounted in said body with a sufficient gaptherebetween so as to cause said piston to assume a floating conditionwhen fluid flows through said gap, said piston compris-ing a hollowcylindrical element having an enlarged flange portion and a cone .as aforward extension of said element, a pilot fluid passage extendingthrough said cone and said valve body and providing a flow path fromsaid inlet passage, through `said hollow cylindrical element to saidfluid discharge passage, `a solenoid-operated plunger for opening andclosing the pilot flow passage at the downstream end thereof, a rstsealing ring mounted on said hollow cylindrical element and butting saidenlarged flange portion, a stationary support member provided in saidfluid inlet passage, a butler member movably mounted on `said supportand a resiliently urging means supported on said support member exertingupon said buffer member an urging force towards the inlet end of saidpilot fluid passage, said buffer being adapted for providing a graduallyincreasing fluid buffering action upon said piston when the latteradvances towards its closing position.

2. Pilot-operated valve assembly as set forth in claim l, furthercomprising a sleeve rigidly mounted on said support member, said ibudermember being in the form of a double headed slide made from a resilientmaterial and said resiliently urging means being in the form of a coiledspring tensioned between said sleeve and one of said heads of `saidslide.

3. Pilot-operated valve assembly as set forth in claim ll, furthercomprising a sleeve rigidly mounted on said support member, said buffermember comprising a rigid pin mounted in said sleeve and having agradually pointed end directing towards the inlet opening of said pilotflow passage.

No references cited.

M. CARY NELSON, Primary Examiner. E. K. FEIN, Examiner.

1. IN A PILOT-OPERATED VALVE ASSEMBLY, THE IMPROVEMENT COMPRISING AVALVE BODY HAVING A FLUID INLET PASSAGE AND A FLUID DISCHARGE PASSAGE, AHOLLOW PISTON SLIDABLY MOUNTED IN SAID BODY WITH A SUFFICIENT GAPTHEREBETWEEN SO AS TO CAUSE SAID PISTON TO ASSUME A FLOATING CONDITIONWHEN FLUID FLOWS THROUGH SAID GAP, SAID PISTON COMPRISING A HOLLOWCYLINDRICAL ELEMENT HAVING AN ENLARGED FLANGE PORTION AND A CONE AS AFORWARD EXTENSION OF SAID ELEMENT, A PILOT FLUID PASSAGE EXTENDINGTHROUGH SAID CONE AND SAID VALVE BODY PROVIDING A FLOW PATH FROM SAIDINLET PASSAGE, THROUGH SAID HOLLOW CYLINDRICAL ELEMENT TO SAID FLUIDDISCHARGE PASSAGE, A SOLENOID-OPERATED PLUNGER FOR OPENING AND CLOSINGTHE PILOT FLOW PASSAGE AT THE DOWNSTREAM END THEREOF, A FIRST SEALINGRING MOUNTED ON SAID